The present invention relates generally to mechanical devices used in surgical procedures to obtain ligation or hemostasis, and more particularly, to a ligation clip used during surgery to clamp around a vessel or duct, such as the cystic duct, and thereby obtain ligation.
It will be appreciated by those skilled in the art that the use of ligation clips to control bleeding during surgical procedures is well known. As described, for example, in U.S. Pat. Nos. 4,976,722 and 4,979,950, prior art clips are generally formed of metal wire, usually a titanium alloy, having a "U-shaped" rectangular cross-section. Such prior art clips often include a grooved pattern machined into the inner or clamping surfaces of the clip, in an attempt to enhance the ability of the clip to remain in position after it is closed around the vessel. Application of the clip to the vessel is normally effected by means of a crushing action produced by a clip applier, such as that disclosed in U.S. Pat. No. 5,030,226. Such crushing actions, of course, permanently deform the clips, making them difficult to remove or re-position.
Prior art surgical ligation clips have several inherent problems. For example, the force applied by the clip to the vessel can be variable and inconsistent from one clip to the next, because of the variation in crushing force applied to the clip by the user. Further, prior art clips have a tendency to slip off the end of the blood vessel stub to which it has been applied, because of the low coefficient of friction associated with the clip, and lack of adequate restraining force provide by the clip. Because of this, separation of the clip from the vessel to which it has been applied, after the wound has been closed, is not uncommon.
It is also common in the prior art to actually form and crush the clip only at the time of its application to the targeted blood vessel. Accordingly, the clip applier mechanism must be relatively large and cumbersome. This is a particular problem in laparoscopic procedures, during which both the clip and clip applier must be inserted through a trocar placed through the patient's external tissues and into the surgical field. Thus, prior art ligation clips used in laparoscopic procedures universally consist of a 10 mm diameter clip applier that can fit only through a trocar having a 10 to 11 mm diameter entry port. Because one goal of laparoscopic surgery is to minimize the size of the entry wound, a surgical ligation clip and clip applier that can be used within a 5 mm diameter trocar port is highly desirable.
What is needed, then, is a surgical ligation clip that can be easily pre-formed into a shape that presents a minimal cross-sectional area, that can be easily applied to a vessel and that, when applied, will impart a consistent hemostatic force to the vessel while resisting separation from the vessel stub. This device is presently lacking in the prior art.